On-chip RF shields with backside redistribution lines

ABSTRACT

Structures of a system on chip and methods of forming a system on chip are disclosed. In one embodiment, a method of fabricating the system on chip includes forming a through substrate opening from a back surface of a substrate, the through substrate opening disposed between a first and a second region, the first region comprising devices for RF circuitry and the second region comprising devices for other circuitry. The method further includes forming patterns for redistribution lines on a photo resist layer, the photo resist layer disposed under the back surface, and filling the through substrate opening and the patterns for redistribution lines with a conductive material.

This is a divisional application of U.S. application Ser. No.12/242,487, which was filed on Sep. 30, 2008, and is incorporated hereinby reference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application relates to the following commonly assignedco-pending applications each of which is hereby incorporated herein byreference:

Patent Issue Attorney Docket Number Ser. No. Filing Date Date Number12/242,698 2008 Sep. 30 INF 2008 P 50667 US 13/037,446 2011 Mar. 01 INF2008 P 50667 US01 12/242,688 2008 Sep. 30 INF 2008 P 50669 US 12/242,5212008 Sep. 30 INF 2008 P 50762 US 12/242,556 2008 Sep. 30 INF 2008 P50764 US

TECHNICAL FIELD

This invention relates generally to electronic devices, and moreparticularly to on-chip RF shields with backside redistribution lines.

BACKGROUND

Semiconductor devices are used in many electronic and otherapplications. Semiconductor devices comprise integrated circuits thatare formed on semiconductor wafers by depositing many types of thinfilms of material over the semiconductor wafers, and patterning the thinfilms of material to form the integrated circuits.

There is a demand in semiconductor device technology to integrate manydifferent functions on a single chip, e.g., manufacturing analog anddigital circuitry on the same die. In such applications, many differentcomponents such as digital, analog or RF circuitry are integrated into asingle chip. However, such integration creates additional challengesthat need to be overcome. For example, integration of multiplecomponents results in interference between various components. RFcircuits operating at high frequencies produce extraneouselectromagnetic radiation that interferes with the operation of othercomponents in the integrated system on chip. This problem deteriorateswith subsequent technology generations as operating frequenciescontinuously increase. Aggressive integration of multiple components ina single chip requires the need to eliminate such interference without asignificant increase in production costs.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, andtechnical advantages are generally achieved, by embodiments of thepresent invention.

Embodiments of the invention include structures for shieldingsemiconductor components on a system on chip comprising an RF componentfrom electromagnetic radiation originating from the RF circuitry of theRF component. In accordance with an embodiment of the present invention,a method of fabricating the system on chip comprises forming a throughsubstrate opening from a back surface of a substrate, the throughsubstrate opening disposed between a first and a second region, thefirst region comprising devices for RF circuitry and the second regioncomprising devices for other circuitry. The method further comprisesforming patterns for redistribution lines on a photo resist layer, andfilling the through substrate opening and the patterns forredistribution lines with a conductive material.

The foregoing has outlined rather broadly the features of an embodimentof the present invention in order that the detailed description of theinvention that follows may be better understood. Additional features andadvantages of embodiments of the invention will be describedhereinafter, which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiments disclosed may be readily utilized as a basisfor modifying or designing other structures or processes for carryingout the same purposes of the present invention. It should also berealized by those skilled in the art that such equivalent constructionsdo not depart from the spirit and scope of the invention as set forth inthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a bottom view of a system on chip with a conductiveshield comprising redistribution lines formed under the RF component, inaccordance with an embodiment of the invention;

FIG. 2, which includes FIGS. 2 a-2 d, illustrates a bottom view of asystem on chip and illustrates redistribution lines forming an RF shieldaround the RF component, in accordance with embodiments of theinvention;

FIG. 3 illustrates a bottom view of a system on chip illustratingredistribution lines forming the RF shield, wherein active throughsubstrate vias and redistribution links are disposed between theredistribution lines;

FIG. 4, which includes FIGS. 4 a and 4 b, illustrates a cross-section ofa through substrate conductor forming a vertical shield, wherein FIG. 4a illustrates a completely filled through substrate conductor and FIG. 4b illustrates a partially filled through substrate conductor, inaccordance with an embodiment of the invention;

FIG. 5, which includes FIGS. 5 a-5 j, illustrates a cross-section of anRF shield comprising a through substrate conductor in various stages offabrication, in accordance with an embodiment of the invention;

FIG. 6 illustrates a cross-section of an RF shield comprising a throughsubstrate conductor in various stages of fabrication, in accordance withan embodiment of the invention;

FIG. 7 illustrates a flow chart of the process illustrated in FIGS. 5and 6, in accordance with an embodiment of the invention;

FIG. 8 illustrates a flow chart of the process for forming an RF shieldcomprising a through substrate conductor in various stages offabrication, in accordance with an embodiment of the invention; and

FIG. 9 illustrates a flow chart of the process for fabrication of an RFshield, in accordance with an embodiment of the invention.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments arediscussed in detail below. It should be appreciated, however, that thepresent invention provides many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

The present invention will be described with respect to preferredembodiments in a specific context, namely, a structure comprisingredistribution lines forming an RF shield. In various embodiments, theinvention avoids the use of separate shielding layers or structuresoutside the chip (for example, additional packaging layers). The presentinvention avoids expensive fabrication costs by integrating the RFshield on-chip rather than being separately attached to the chip.Further, being an integrated RF shield, the manufacturing steps arecommonly shared with other components already being used in thefabrication of the system on chip (SoC). Although illustrated withrespect to shielding adjacent components on an SoC, the invention may beapplied to shielding single chips from adjacent chips.

According to SoC requirements, analog, RF, digital, and memory blocksmust all coexist on-chip while interacting minimally (such as generatingminimal noise and being highly immune to the received noise). Inparticular, as operating frequencies increase with scaling, RFcomponents operating at high GHz frequencies emit electromagneticradiation that interferes with other neighboring components. In variousembodiments of the present invention, a conductive shield surrounds theRF components to minimize this interference. The conductive shieldblocks out the electromagnetic radiation generated by the RF circuitryfrom reaching other components of the SoC.

To minimize parasitic elements, conventional redistribution lines suchas used for carrying input/output signals and power are designed to beof the shortest length. However, in contrast, in various embodiments,the backside redistribution lines of the RF shield are formed as a largestructure to maximize shielding of electromagnetic radiation emitted bythe operating RF device.

A structural embodiment of the invention illustrating a backside view ofa conductive cage will be first described using FIG. 1. Embodiments ofthe invention illustrating bottom cross-sectional views will bedescribed using FIGS. 2 and 3. Vertical cross-sectional views ofembodiments of invention will be described using FIG. 4. Embodiments ofmethods of fabrication of backside redistribution lines coupled tothrough substrate conductors will be illustrated in FIGS. 5, 7 and 9 andflow charts of FIGS. 6, 8 and 10.

An embodiment of the invention is illustrated in FIG. 1. The SoC chip 99illustrated in FIG. 1 comprises an RF circuit 1 along with othercomponents. In one embodiment, the SoC chip 99 comprises digital logiccomponent 2, analog component 3, non-volatile memory 4, and SRAMcomponent 5. In various embodiments, less or more components may bepresent.

In various embodiments, electromagnetic radiation emitted by the RFcomponent 1 is shielded by the RF shield 8. The RF shield 8 comprises aon-chip three dimensional structure enclosing the RF component 1, and isformed as part of the SoC 99. The RF shield 8 comprises a bottom shield40 disposed on the bottom of the SoC 99, in one embodiment. In variousembodiments, the bottom shield 40 is disposed underneath the RFcomponent 1 and/or around the RF component 1. In various embodiments,this arrangement does not require use of additional chip area, and henceinvolves no additional area penalty. The bottom shield 40 also comprisesopenings for placing routing to adjacent components.

In various embodiments described in this disclosure, the bottom shield40 comprises backside redistribution lines 52. The backsideredistribution lines 52 may comprise different shapes and arranged tominimize fabrication costs while maximizing the design of the throughsubstrate conductors.

FIG. 2 illustrates an embodiment of the invention and describes abackside of a system on chip illustrating the backside redistributionlines along with through substrate conductors forming a portion of an RFshield. In various embodiments described herein, the redistributionlayers comprising backside redistribution lines 52 are formed on thewafer backside for RF shield 8 or EM-shield. The backside redistributionlines 52 are disposed on the backside of the substrate 10 (e.g. backsideof wafer or chip) and connected to a node coupled to ground potential.

Referring to FIGS. 2 a and 2 b, a backside view of a system on chipillustrates one embodiment of the backside redistribution lines 52forming the RF shield 8. While FIG. 2 a illustrates the backsideredistribution lines 52 aligned parallel to each other, FIG. 2 billustrates further backside redistribution lines 52 alignedperpendicular to the first set of backside redistribution lines 52illustrated in FIG. 2 a. Hence, FIG. 2 b illustrates a mesh-likestructure formed by the backside redistribution lines 52. The backsideredistribution lines 52 are connected to through substrate conductors 25disposed around the RF component 1. The backside redistribution lines 52are connected to other parts of the overall RF shield, e.g. to theRF-grids, fences or meshes in the on-chip interconnect layers and to thefences or grids of the through substrate conductors 25.

In various embodiments, the through substrate conductors 25 are formedby etching the wafer from the top surface, or formed later during thefabrication of the backside redistribution lines 52 by etching a throughsubstrate opening from the backside of the substrate 10. All parts ofthe RF shield are coupled to a ground potential node. The spacingbetween individual backside redistribution lines 52 is smaller than thewavelength of the RF frequency being shielded. In various embodiments,the backside redistribution lines 52 are designed based on the expectednoise of the operating RF component 1. In one embodiment, the spacingbetween backside redistribution lines 52 is about 100 μm or less isselected to shield RF frequencies up to 1000 GHz, while a spacing ofabout 10 mm is selected to shield RF frequencies up to 10 GHz. Hence, invarious embodiments, the spacing can be optimized for the operatingrange of the RF circuit. In various embodiments, the backsideredistribution lines 52 comprise low resistivity metals.

In various embodiments, the backside redistribution lines 52 comprises ametallic material comprising copper, aluminum, silver, gold, nickel,palladium, tungsten, or a combination thereof. In some embodiments, thebackside redistribution lines 52 comprise additional barrier liners. Inone embodiment, the backside redistribution lines 52 are lined with amaterial comprising Ta, TaN, TiW, Ti, TiN, Ru, W, WN, WCN, or acombination thereof. In one embodiment, the backside redistributionlines 52 comprise a silicide material, for example, comprising nickelsilicide, cobalt silicide, titanium silicide, platinum silicide, orcombinations thereof.

FIGS. 2 c and 2 d illustrate additional embodiments of the backsideredistribution lines 52 wherein the backside redistribution lines 52 areformed along the periphery of the RF component and coupled to the frontside circuitry through the through substrate conductors 25.

In some embodiments, the backside redistribution lines 52 may provideconnections (not illustrated) coupling the front side circuitry to othercomponents of the chip using the through substrate conductors 25.

FIG. 3 illustrates a magnified backside view of the RF component 1. Thebackside redistribution lines 52 comprise openings as well as largergaps to allow routing of connections. The backside redistribution layeris used for transmitting signals within a chip or between differentchips or I/O or power/ground connections. The backside redistributionlayer is disposed under the RF component as well as under the rest ofthe system on chip, in various embodiments. The connections to thefrontside circuitry of the chip is provided by the through viaconductors 25, for example, through substrate vias 21. In oneembodiment, pads for flip-chip or micro bumps are disposed between thebackside redistribution lines 52. In various embodiments, this ispossible because moderate RF frequencies, for example, frequencies up to50 GHz, can include openings between backside redistribution lines 52 ofabout several mm without degrading shielding. Flip chips or micro bumpsthat are about 100 μm to about 500 μm in diameter are hence placedbetween the backside redistribution lines 52 without compromising thecapability of the RF shield 8. The (flip chip or micro bump) pads 53 insome embodiments are connected to the through substrate conductors 25 bythe backside redistribution links 54 formed along with the backsideredistribution lines 52. The backside redistribution links 54 provideelectrical coupling of the pads 53 to the frontside of the RF component1 through the through substrate conductors 25. In various embodiments,the backside redistribution links 54 are formed along with the backsideredistribution lines 52 and require no additional processing.

FIG. 4 illustrates vertical cross-sectional views of a through substratevia fabricated in accordance with embodiments of the invention.

Referring to FIG. 4 a, the through substrate via 21 is disposed betweenan RF component 1 comprising RF circuitry, and another component, forexample, a digital logic component 2. The through substrate via 21 formsthe vertical fence 20 shielding the digital logic component 2 from theRF component 1. Both the RF component 1 and the digital logic component2 are disposed in the substrate 10. Examples of the substrate 10 arebulk mono-crystalline silicon substrate (or a layer grown thereon orotherwise formed therein), a layer of (110) silicon on a (100) siliconwafer, a silicon-on-insulator (SOI), or a germanium-on-insulator (GeOI)wafer. In other embodiments, other semiconductors such as silicongermanium, germanium, gallium arsenide, indium arsenide, indiumphosphide, indium gallium arsenide, indium antimonide or others can beused with the wafer. The substrate 10 also includes active componentssuch as transistors or diodes, or passive components such as inductorsor resistors, among others. Active regions are disposed on a top surfaceof the substrate and comprise active devices such as transistors,resistors, capacitors, diodes etc. Metallization levels are disposedover the top surface of the substrate 10. Interconnect layers 60 aredisposed above the substrate 10 and comprise the metallization levelsthat interconnect the circuit.

The through substrate via 21 couples to a landing pad 63 a on the firstmetal level of the interconnect layers 60. The landing pad 63 a is widerthan the width of the through substrate via 21. The landing pad 63 aelectrically connects to the through substrate via 21. If the throughsubstrate via 21 is part of the RF shield 8, the landing pad 63 a iselectrically coupled to a ground potential through the interconnectlayer 60. In some embodiments, the through substrate via 21 is alsoelectrically connected with other parts of the active circuitry throughthe landing pad 63 a.

The first metal level comprises first metal lines 63 disposed over thesubstrate 10. The first metal lines 63 are disposed over a firstmetallization insulation layer 61. The first metallization insulationlayer 61 is disposed over the substrate 10 and around the throughsubstrate via 21. A second metallization insulation layer 62 is disposedover the first metallization insulation layer 61. The first metal lines63 are embedded in the second metallization insulation layer 62. Theinterconnect layer 60 further comprise a first via 64 disposed on thelanding pad 63 a, and a second metal line 65 coupled to the first via64.

A first conductive layer 41 is disposed in the inner region of thethrough substrate via 21, and electrically couples the landing pad 63 ato the backside of the substrate 10. The first conductive layer 41comprises copper, although in other embodiments other conductivematerials such as doped polysilicon, tungsten, aluminum, silver, gold,nickel, palladium, or combination thereof are used.

A sidewall dielectric layer 26 is disposed around the through substratevia 21 and electrically isolates the first conductive layer 41. Thesidewall dielectric layer 26 is an oxide such as silicon oxide, or anitride such as silicon nitride or silicon oxynitride. In someembodiments, the sidewall dielectric layer 26 comprises other low-k orhigh-k dielectric material. In some embodiments, a trench metal liner isdisposed on the sidewalls of the through substrate via 21 over thesidewall dielectric layer 26. The trench metal liner acts as a metaldiffusion barrier for the first conductive layer 41. In someembodiments, the trench metal liner also contains a seed layer usedduring subsequent electroplating processes. In one embodiment, the firstconductive layer 41 is lined with a trench metal liner comprising Ta,TaN, TiW, Ti, TiN, Ru, W, WN, WCN, or a combination thereof.

The through substrate via 21 is coupled to a bottom shield 40 at thebottom. The bottom shield 40 comprises a second conductive layer 42contacting the first conductive layer 41.

FIG. 4 b illustrates an embodiment of the invention, illustrating apartially filled through substrate via 21. Unlike the previousembodiment, FIG. 4 b illustrates a first conductive layer 41 partiallyfilling the through substrate via 21. A second conductive layer 42couples to the first conductive layer 41 and forms the bottom shield 40.A second insulating layer 44 is disposed under the backside of thesubstrate 10 and isolates the second conductive layer 42. A thirdinsulating layer 45 is disposed on the first conductive layer 41 insidethe through substrate via 21.

Embodiments of the invention describing methods of fabrication of the RFshield on the system on chip will be described using FIGS. 5, and 6, andwith respect to flow charts of FIGS. 7 and 8. FIG. 5, which includesFIGS. 5 a-5 j and the flow chart of FIG. 7 describe a method of theembodiment forming a partially filled through substrate via from thebackside of the substrate, whereas FIG. 6, which includes FIGS. 6 a and6 b describes a fully filled through substrate via from the backside ofthe substrate. FIG. 8 illustrates an embodiment of a through substrateopening formed from a front side while using a common process to formthe conductive part of the through substrate via and backsideredistribution lines. The cross-sections are illustrated at a boundarybetween an RF component 1 and another component (for example, digitallogic component 2).

Referring to FIG. 5 a, and as illustrated in flow chart of FIG. 7,active device regions 17 are formed on a side near a top surface of asubstrate 10 during front end processing. The substrate 10 is typicallya semiconductor wafer. The active device regions 17 or active circuitryincludes transistors, diodes, resistors, capacitors, inductors or othercomponents used to form the active devices for the RF component and theother component (digital logic component 2).

Next, metallization is formed in the interconnect layer 60 over theactive device regions 17 to electrically contact and interconnect theactive device regions 17. The metallization and active circuitrytogether form a completed functional integrated circuit. In other words,the electrical functions of the chip can be performed by theinterconnected active circuitry. In logic devices, the metallization mayinclude many layers, e.g., nine or more, of copper. In memory devices,such as DRAMs, the number of metal levels may be less and may bealuminum.

Returning to the flow chart of FIG. 5, the components formed during thefront-end processing are interconnected by back end of line (BEOL)processing. During this process, contacts are made to the semiconductorbody and interconnected using metal lines and vias. As discussed above,modern integrated circuits incorporate many layers of vertically stackedmetal lines and vias (multilevel metallization) that interconnect thevarious components in the chip. For simplicity only the first and secondmetal levels are shown. However, more or less metal levels may bepresent in various embodiments.

Referring to FIG. 5 a and flow chart of FIG. 7, the substrate 10 isthinned exposing a lower surface 18 by grinding to a desired thickness.The typical thickness of the substrate 10 after thinning is about 3 μmto about 300 μm. In different embodiments, the thinning may also beperformed chemically or using a plasma etch. For example, a modifiedplasma etch may be used to thin the silicon wafer from the backside.Such techniques have the additional advantage of not damaging the frontside. The advantage of thinning the wafer is to shorten the length ofthe through-vias, which enhances the electric properties and speeds upthe via etch processing and creates a via with relatively verticalsidewall. The thinned substrate 10 may be attached to a suitable carrierfor handling.

Referring to FIG. 5 b, masking layers are deposited over the lowersurface 18 of the substrate 10 and patterned. A second insulating layer44 is deposited over the lower surface 18 of the wafer. A first hardmask layer 46 is deposited on the lower surface 18 of the substrate 10.The first hard mask layer 46 may be a single layer or comprise multiplelayers. The first hard mask layer 46 protects the lower surface 18 andthe second insulating layer 44 during the through trench etch. The firsthard mask layer 46 is selected based on the selectivity to the throughtrench etch process. For example, in one embodiment, a high densityplasma with a fluorine chemistry is used to etch the through substrateopening, and the first hard mask layer 46 comprises a SiO₂ hard mask. Afirst photo resist layer 47 is spun over the first hard mask layer 46.

The landing pads 63 a are aligned to a mask using a mask aligner. Themask aligner comprises an infra red mask aligner to detect landing pads63 a, although in other embodiments other suitable techniques may beused. The first photo resist layer 47 is exposed and patterned. Thefirst hard mask layer 46 and underlying second insulating layer 44 areetched to expose the lower surface 16 using the patterned first photoresist layer 47 as a mask.

As illustrated in FIG. 5 c, a high density plasma process in an RFplasma chamber is used to form a through substrate opening 35. An etchstep is carried out using a fluorine based plasma. However, fluorinebased etches are isotropic and result in non vertical trench sidewalls.Hence, a deposition step is carried out by introducing a polymerproducing gas into the plasma chamber. The polymer producing gasdeposits a polymer layer on the exposed sidewalls forming a temporaryetch stop layer. The polymer layer is not formed on the exposed bottomsurface of the trench due to the high energy of the impinging ions. Anypolymer deposited on the bottom surface of the trench is broken up bythe high energy of the impinging ions. The through substrate openingprocess is carried out in sequential etch and deposition steps. Avertical opening may thus be produced. For example, the fluorine etchstep may comprise a SF₆ etchant, whereas the polymer producing gas maycomprise C₄F₈. The etch and deposit steps may be repeated many times,e.g., about 100 times to about 500 times, to form the through substrateopening 35. In other embodiments, other types of reaction ion etchprocesses may be used. After the etch step, the through substrateopening 35 may comprise any suitable vertical shape such as cylindrical,annular, faceted, trench etc.

The etch proceeds by etching the substrate 10 and opens the firstmetallization insulation layer 61 for etching. Ideally, the throughsubstrate etch process should stop on the landing pad 63 a to maximizeelectrical contact. Further, the interconnect stack over the landingpads 63 a should have at least several microns of remaining interconnectmaterial to support the structure mechanically.

The end point of the etch process is typically determined from ananalysis (e.g., optically) during etching. For reliable detection, thethickness of the metal lines etched should be higher than about 700 nm.Hence, an etch process may etch beyond the first metal lines 63, butstop in the insulation layer 60. In the absence of the first vias 64 asillustrated in embodiments of the invention, such a through substrateopening 35 is not electrically connected to front end interconnects. Thepresence of first vias 64 and subsequent levels such as second metalline 65 enables electrical connectivity independent of the etch stoppoint.

A sidewall dielectric layer 26 is next deposited over the throughsubstrate opening 35. The sidewall dielectric layer 26 electricallyisolates the trench fill material from active devices. The sidewalldielectric layer 26 is deposited conformally over the exposed surfacesof the through substrate opening 35 (FIG. 5 d). The sidewall dielectriclayer 26 may be deposited by a suitable low temperature process such asplasma enhanced CVD and/or organic vapor phase deposition. The sidewalldielectric layer 26 is anisotropically etched forming a sidewall on thethrough substrate opening 35 (FIG. 5 e). On the planar backside surfacethe dielectric layer 26 and any remaining first hard mask layer 46 isremoved, exposing the second insulation layer 44.

Referring to FIG. 5 f, a barrier liner 48 is deposited prior to fillingthe through substrate opening 35 with the fill material. The barrierliner 48 is conformal, and may comprise a single layer of Ta, TaN, W,WN, WCN, WSi, Ti, TiN and/or Ru as examples. The barrier liner 48 istypically used as a barrier layer for preventing metal from diffusinginto the underlying substrate 10 and sidewall dielectric layer 26. Thebarrier liner 48 is deposited using, for example, RF magnetronsputtering. The barrier liner 48 may comprise a seed layer of copperover the diffusion barrier layer. This seed layer may be depositedconformally, for example, using a PVD sputtering or a metal-organic CVD(MOCVD) process.

Referring next to FIG. 5 g, a second photo resist layer 49 is depositedon the back surface of the substrate 10. In various embodiments, thesecond photo resist layer 49 is a thick layer of photo resist comprisinga thickness of several microns. The second photo resist layer 49 ispatterned using a photo lithography step (FIG. 5 h). The photolithography step is performed through a mask with patterns forredistribution lines and through substrate openings 35. The photolithography step exposes the barrier liner and the optional seed layerof copper over the barrier 48.

As illustrated in FIG. 5 i, a first conductive layer 41 is thendeposited on the barrier liner 48 using, for example, an electroplatingprocess. The first conductive layer 41 is thus deposited in between thesecond photo resist layer 49. The first conductive layer 41 is thusdeposited both inside the through substrate opening 41 and on patternsforming for redistribution lines. The first conductive layer 41partially fills the through substrate opening 35. A partial fill isadvantageous as it requires less electroplating time and alleviatesstress during subsequent processing.

In one embodiment, the first conductive layer 41 comprises copper. In adifferent embodiment, the first conductive layer 41 comprises tungsten.If the first conductive layer 41 comprises tungsten, preferably abi-layer seed layer comprising CVD titanium nitride and silicon dopedtungsten are used. Similarly, in some embodiments, doped poly-silicon,silver, gold and/or aluminum may be deposited inside the throughsubstrate opening 35 to form the through substrate conductor 25.Remaining second photo resist layer 49 is stripped to expose the barrierliner 48. The barrier liner 48 is removed by wet or dry etching toexpose the underlying second insulating layer 44.

Referring to FIG. 5 j, a third insulating layer 45 is deposited over thesecond insulating layer 44 and the first conductive layer 41. The firstconductive layer 41 under the backside of the substrate 10 forms thebackside redistribution lines 52, while the first conductive layer 41inside the through substrate opening 35 forms the conductive element ofthe through substrate conductor 25. In various embodiments, thesubstrate 10 is subsequently diced into individual chips after formingthe backside redistribution lines 52. Thus the backside redistributionlines 52 and the through substrate conductor 25 are formedsimultaneously using a single process avoiding expensive processing.

In a very similar approach a completely filled through substrate openingcan be realized. However, in this embodiment, during the pattern platingstep of copper in between the resist openings, a thicker copper film isdeposited. This thicker copper film completely fills and overfills thethrough substrate openings. Hence, unlike the prior embodiment, asillustrated in FIG. 6, the first conductive layer 41 completely fillsthe through substrate opening 35.

As described above in various embodiments, in the same deposition stepthe conductive material for the metal lines of the backsideredistribution layer 52 and the optional flip-chip or micro-bump pads isdeposited.

FIG. 7 gives a schematic flow chart (as illustrated in FIGS. 5 and 6) ofprocess sequence after the front side processing of the wafer usingembodiments of the invention. The metal lines of the backsideredistribution layer can be used as part of the RF shield, as signalwires, as wires to provide power and ground or as wires to connect tothe flip-chip or micro-bump pads.

FIG. 8 illustrates a schematic process flow for another embodiment ofthe invention illustrating a through substrate via and redistributionlines formed simultaneously.

Unlike the prior embodiments, in this embodiment the opening forfabricating the through substrate opening is formed from a top surfaceof the workpiece. This may be preferable in some embodiments, as itavoids resistivity problems arising from mismatched alignment orinability to stop the etch on landing pads.

A first opening is etched from the frontside after forming the activedevices. The first opening is formed through the Si substrate and thefirst metallization insulating layer. A sidewall dielectric liner isdeposited over the first opening, the sidewall dielectric liner formingan insulating liner. The sidewall dielectric liner is an oxide ornitride material layer. Up to this step the process sequence isidentical to the sequence described in co-pending application Ser. No.12/242,521, filed on Sep. 30, 2008.

A sacrificial material is spun on or deposited into the first opening.The sacrificial material comprises any material with good etchselectivity with the sidewall dielectric layer and the metal pads whichwill be built on-top. Examples of sacrificial material include spin onorganic materials used as bottom anti-reflective coatings, as well asspin on glass materials or poly-silicon material.

Continuing as described in previously mentioned co-pending application,a second metallization insulating layer is deposited over the firstmetallization insulating layer. The second metallization insulatinglayer is patterned for first metal lines. An optional protective caplayer may be deposited over the sacrificial material. In variousembodiments, the protective cap layer also forms the barrier liner, forexample, a metallic nitride such as TiN or TaN. The protective cap layercomprises an etch selectivity relative to the sacrificial material suchthat the protective cap layer is not etched while removing thesacrificial material. The first metal lines are formed by electroplatinga conductive material. Subsequent levels of metallization, passivationlayers and contact pads are subsequently formed. After finishing thefrontside processing, the substrate is thinned from the backside toexpose a back surface and the sacrificial material in the throughsilicon opening. A dielectric material is deposited on the backside ofthe wafer and opened by a lithography and etching sequence to exposeagain the sacrificial material in the through substrate openings. In thenext step the sacrificial material in the through substrate openings isetched out by a wet or dry etch process. This wet or dry etch processneeds to be selective to the sidewall dielectric layer of the throughsubstrate openings and the metallic liner and metal of the metal coverof the through substrate opening built in the interconnect levels of thewafer frontside.

As described in prior embodiments (e.g., FIGS. 5 f-5 j), making use of ametallic liner and seed layer, a patterned thick photoresist layer,backside redistribution lines 52 and through substrate vias 21 areformed simultaneously by filling the through substrate opening and theredistribution layer openings in the photo resist with a conductivematerial from the back surface. The through substrate opening is filledup with a first conductive layer 41 forming the through substrate vias21 and backside redistribution lines 52.

Although the sacrificial material is removed in this embodiment, in someembodiments the sacrificial material may be converted into a conductor.For example, if the sacrificial material comprises polysilicon, afterthinning the substrate, a silicidation step may be performed from thebackside to convert the sacrificial material into a metal silicide.

In another embodiment of the invention as illustrated in flow chart ofFIG. 9, the through substrate via is fabricated during the front sideprocessing of the wafer as described in co-pending application Ser. No.12/242,521, filed on Sep. 30, 2008. After completing the front sideprocessing, the substrate is thinned from the backside of the waferuntil the conductive filling of the through substrate via is exposed. Inthe next step, a dielectric layer is deposited on the backside of thewafer. The dielectric layer comprises silicon oxide, silicon nitride,silicon carbide, silicon carbonitride, a polymer dielectric, BCB,polyimide, photoimide, or combination thereof. A photoresist isdeposited over the dielectric layer and exposed and developed in aphotolithography step to define openings in the photoresist over thethrough substrate vias. In an etching step, the openings are transferredinto the dielectric layer exposing the conductive filling of the throughsubstrate openings. A metal liner and a seed layer are deposited toelectrically contact the conductive filling of the through silicon via.The metal liner may comprise Ta, TaN, TiW, Ti, TiN, Ru, W, WN, WCN orcombinations thereof, and the seed layer may comprise copper, silver,gold, tungsten, aluminum, ruthenium or combinations thereof. After themetal liner and seed layer deposition, another thick photoresist isdeposited, exposed and developed in order to define the openings for theconductive redistribution lines on the wafer backside. In a patternplating step or any other suitable deposition step the conductivematerial for the redistribution layer is deposited in between theopenings of the resist. The conductive material for the redistributionlayer on the wafer backside may comprise copper, silver, gold, tungsten,aluminum, ruthenium or combinations thereof. After the deposition of theconductive material for the redistribution layer, the photo resist isstripped followed by an etching step to remove the seed layer andmetallic liner previously covered by the photoresist in between themetal lines of the redistribution layer. The conductive redistributionlayer deposited in this process sequence is used to build the backsidepart of the RF shield and is connected to all other parts of theRF-shield by the through silicon vias. All parts of the RF shield areconnected to the same ground potential. Other parts of the backsideredistribution layer may be used as wires for signal transport, powerand ground connections or to build flip-chip or micro-bump pads toconnect to other chips, substrates or printed circuit boards.

Although embodiments of the present invention and their advantages havebeen described in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the invention as defined by the appended claims.For example, it will be readily understood by those skilled in the artthat many of the features, functions, processes, and materials describedherein may be varied while remaining within the scope of the presentinvention.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, there areprocesses, machines, manufacture, compositions of matter, means,methods, or steps, presently existing or later to be developed, thatperform substantially the same function or achieve substantially thesame result as the corresponding embodiments described herein that maybe utilized according to the present invention. Accordingly, theappended claims are intended to include within their scope suchprocesses, machines, manufacture, compositions of matter, means,methods, or steps.

What is claimed is:
 1. A method of forming a system on chip, the methodcomprising: forming a through substrate opening from a back surface of asubstrate, the through substrate opening disposed between a first and asecond region of the substrate, the first region comprising devices forRF circuitry proximate a top surface opposite the back surface and thesecond region comprising devices for other circuitry proximate the topsurface opposite the back surface; forming patterns for redistributionlines within a photo resist layer disposed at the back surface; andforming a redistribution layer comprising first and secondredistribution lines and forming a through substrate conductor byfilling the through substrate opening and the patterns forredistribution lines with a conductive material, wherein the firstredistribution lines are formed under the first region and isolated fromthe substrate by an insulating layer, wherein the second redistributionlines are formed under the second region and coupled to activecircuitry, wherein the first redistribution lines are coupled to aground potential node by the through substrate conductor.
 2. The methodof claim 1, further comprising: forming devices for RF circuitry and forother circuitry at a top surface before forming the through substrateopening, the top surface being opposite to the back surface; forminginterconnect layers before forming the through substrate opening, theinterconnect layers interconnecting the devices; and after forming theinterconnect layer, thinning the substrate from a backside to expose theback surface.
 3. The method of claim 1, wherein forming the throughsubstrate opening comprises: etching from the back surface using areactive ion etch, wherein the reactive ion etch starts from the backsurface and etches through the substrate and stops on a landing pad, thelanding pad being disposed in an insulating layer disposed over thesubstrate.
 4. The method of claim 1, wherein forming patterns forredistribution lines within a photo resist layer comprises: depositingthe photo resist layer; exposing the photo resist layer using a photolithography step; and developing the photo resist layer to form thepatterns for redistribution lines, wherein the developing also removesthe photo resist layer from the through substrate opening.
 5. The methodof claim 4, wherein filling the through substrate opening and thepatterns for the redistribution lines with a conductive materialcomprises electroplating the conductive material to fill the throughsubstrate opening.
 6. The method of claim 5, wherein filling the throughsubstrate opening and the patterns for the redistribution lines with aconductive material comprises: depositing a conductive material layerinto the through substrate opening and the patterns for theredistribution lines; and depositing an insulating material layer intothe through substrate opening, the insulating material layer depositedon the conductive material layer.
 7. A method of forming a system on achip comprising RF circuitry, the method comprising: forming throughsubstrate openings from a back surface of a substrate, the throughsubstrate openings arranged around a first region, the first regioncomprising devices for the RF circuitry on a top surface, the topsurface being opposite to the back surface; and forming throughsubstrate conductors and redistribution lines simultaneously by at leastpartially filling the through substrate openings and a patterned resistdisposed under the back surface with a conductive material, thepatterned resist comprising patterns for redistribution lines, whereinforming the through substrate conductors and redistribution linessimultaneously comprises using a electroplating process to deposit aconductive layer into the through substrate openings and the patternsfor redistribution lines.
 8. The method of claim 7, wherein arrangingthe through substrate openings around the first region comprises formingmultiple rows of through substrate openings around the first region,each row staggered relative to a neighboring row of the throughsubstrate openings.
 9. The method of claim 7, further comprising fillingthe through substrate openings by depositing an insulating materiallayer into the through substrate openings.
 10. A method of forming asystem on a chip comprising RF circuitry, the method comprising: formingthrough substrate openings from a back surface of a substrate, thethrough substrate openings arranged around a first region, the firstregion comprising devices for the RF circuitry on a top surface, the topsurface being opposite to the back surface, wherein forming throughsubstrate openings from the back surface of the substrate comprises:forming an opening within the substrate from the top surface, fillingthe opening with a sacrificial material, capping the sacrificialmaterial with a protective cap layer, and removing the sacrificialmaterial from the back surface to form the through substrate opening;and forming through substrate conductors and redistribution linessimultaneously by at least partially filling the through substrateopenings, and a patterned resist disposed under the back surface with aconductive material, the patterned resist comprising patterns forredistribution lines.
 11. A method for forming a semiconductorintegrated circuit chip, the method comprising: forming a firstsemiconductor component having a first active circuitry in a firstregion of a semiconductor substrate; forming a second semiconductorcomponent having a second active circuitry in a second region of thesemiconductor substrate, the first and the second semiconductorcomponents sharing a common boundary, the first and the secondsemiconductor components being formed proximate a top surface of thesemiconductor substrate than an opposite back surface of thesemiconductor substrate; forming an insulating layer under the backsurface of the semiconductor substrate; forming first metal lines underthe insulating layer, the first metal lines being formed under the firstsemiconductor component and isolated from the semiconductor substrate bythe insulating layer; forming second metal lines under the insulatinglayer, the second metal lines being formed under the secondsemiconductor component, the first and the second metal lines being partof a back side metallization layer; coupling the first metal lines to aground potential node; and coupling the second metal lines to the secondactive circuitry.
 12. The method of claim 11, wherein the firstsemiconductor component comprises an RF component.
 13. The method ofclaim 11, wherein the first and the second metal lines comprise copper.14. The method of claim 11, wherein the first and the second metal linescomprise a metal selected from the group consisting of gold, silver,aluminum, tungsten, and combinations thereof.
 15. The method of claim11, further comprising: forming third metal lines under the insulatinglayer, the third metal lines being formed under the first semiconductorcomponent, wherein the third metal lines are perpendicular to the firstmetal lines.
 16. The method of claim 11, further comprising forming athrough substrate conductor in the semiconductor substrate, whereinforming the first metal lines comprises coupling with the throughsubstrate conductor.
 17. A method of forming a semiconductor integratedcircuit chip, the method comprising: forming a first semiconductorcomponent having a first active circuitry in a first region of asemiconductor substrate; forming a second semiconductor component havinga second active circuitry in a second region of the semiconductorsubstrate, the first and the second semiconductor components sharing acommon boundary, the first and the second semiconductor components beingformed proximate a top surface of the semiconductor substrate than anopposite back surface of the semiconductor substrate; forming aninsulating layer under the back surface of the semiconductor substrate;forming an opening within the semiconductor substrate from the topsurface; filling the opening with a sacrificial material; capping thesacrificial material with a protective cap layer; removing thesacrificial material from the back surface to form a through substrateopening; depositing a conductive material layer into the throughsubstrate opening to form a through substrate conductor; forming firstmetal lines under the insulating layer, the first metal lines beingformed under the first semiconductor component and isolated from thesemiconductor substrate by the insulating layer; forming second metallines under the insulating layer, the second metal lines being formedunder the second semiconductor component, the first and the second metallines being part of a back side metallization layer; coupling the firstmetal lines to a ground potential node; and coupling the second metallines to the second active circuitry.
 18. The method of claim 16,wherein forming a through substrate conductor comprises: etching anopening from the back surface using a reactive ion etch, wherein thereactive ion etch starts from the back surface and etches through thesubstrate and stops on a landing pad, the landing pad being disposed ina second insulating layer disposed over the semiconductor substrate. 19.The method of claim 16, wherein the first metal lines are coupled to theground potential node via the through substrate conductor.
 20. Themethod of claim 1, wherein forming a through substrate opening from aback surface of a substrate comprises: forming an opening within thesubstrate from the top surface, the top surface being opposite to theback surface; filling the opening with a sacrificial material; cappingthe sacrificial material with a protective cap layer; and removing thesacrificial material from the back surface to form the through substrateopening.
 21. The method of claim 7, wherein forming through substrateopenings from a back surface of a substrate comprises: etching from theback surface using a reactive ion etch, wherein the reactive ion etchstarts from the back surface and etches through the substrate and stopson a landing pad, the landing pad being disposed in an insulating layerdisposed over the substrate.
 22. The method of claim 16, wherein forminga through substrate conductor comprises forming a through substrateopening from the top surface and filling the through substrate openingwith a conductive material.
 23. The method of claim 16, wherein forminga through substrate conductor comprises forming an opening within thesemiconductor substrate from the top surface and depositing a conductivematerial layer into the through substrate opening from the back surfaceto form a through substrate conductor.
 24. The method of claim 17,wherein the first semiconductor component comprises an RF component. 25.The method of claim 17, wherein the first and the second metal linescomprise copper.
 26. The method of claim 17, wherein the first and thesecond metal lines comprise a metal selected from the group consistingof gold, silver, aluminum, tungsten, and combinations thereof.
 27. Themethod of claim 7, wherein the redistribution lines comprise firstredistribution lines disposed under the RF circuitry, and secondredistribution lines disposed under other circuitry of the substrate,wherein the first redistribution lines are coupled to a ground potentialnode, wherein the second redistribution lines are coupled to othercircuitry on the substrate.
 28. The method of claim 27, wherein thefirst redistribution lines comprise a first set of metal lines orientedin a first direction.
 29. The method of claim 28, wherein the firstredistribution lines comprise a second set of metal lines oriented in asecond direction perpendicular to the first direction.